The commercial need for in-building cellular coverage is driving businesses to invest in small cells. But with an industry in flux is now the right time to do so? Sam Fenwick investigates

The quest for cellular signal can often be a frustrating one, especially in big cities. The new glass-covered buildings popping up across our skylines are built with materials that are both energy efficient and block RF signals. With land at a premium the trend towards greater use of basements is also making it harder to get a signal in many places.

And these signal problems are starting to affect businesses. Nick Johnson, CTO of ip.access, gives the example of a company in central London that provides shared workspace. It had less than 50 per cent occupancy and didn’t know why until a survey of people that had decided not to rent space made it clear a lack of multi-operator cellular coverage was the reason. “As soon as they provided that – at some expense – their occupancy levels rose to about 95 per cent,” he says.

Jonathan Freeman, director of small cells and in-building at Arqiva, says much of small cells’ appeal comes from helping employees work more flexibly and supporting bring your own device. However, if employees are free to choose their network operator then multi-operator small cells will be needed.

Multi-operator coverage requires one set of RF equipment per operator and many venues that could benefit from it are below the size and capacity that interests operators. Graham Payne, CEO of OpenCell, says his company is the only business in the UK offering multi-operator small cell installations and can deliver them for less than £200,000 for a very large site, with some installations costing less than £50,000. Currently OpenCell is only installing 3G small cells, but it is looking to move to a 3G/4G solution. Its 3G system provides 7-8 Mbps download speeds and 1.5 Mbps upload speeds.

Until the majority of UK radio handsets support voice-over-LTE, 3G in-building coverage will still be required for voice calls. Payne estimates that the costs associated with upgrading a small cell deployment from 3G to 4G is roughly 50 per cent of the initial cost, due to the cost of neutral infrastructure such as IP switches, routers and backhaul.

Both SpiderCloud Wireless and ip.access offer small cells with self-organising properties. SpiderCloud Wireless’ system uses a central controller (called a Service Node) that manages all the small cells in an installation to allow soft handovers between them and between the small cell network and the macro network. The system continually monitors the RF environment and refines each cell’s radio parameters accordingly. ip.access’ system doesn’t require a central node. The company can offer its Viper2020 solution for small cells as a service, where each deployment is paid for via a monthly fee.

David Chambers, founder and senior analyst at ThinkSmallCell, says this architectural difference means that SpiderCloud’s system is “primarily aimed at medium to large enterprise buildings”, whereas ip.access’ small cell products “are very suited to everything from the individual small home or office user to medium-sized buildings”.

When it comes to deploying in-building small cells, he notes that it’s important to ensure that the handovers to and from the macro network(s) occur at the building’s entry and exit points and that “they don’t happen if you’re standing at the window halfway up a towerblock”. Chambers adds that this becomes difficult with verandas or balconies where users’ devices may see many macrocells and the signal from the indoor small cells might not be as strong and the industry has developed best practice radio planning techniques to avoid and resolve these issues.

Alastair Williamson, CEO of Ranplan, has seen installations where a small cell is installed in the ceiling but a metre away from an external window. “We saw that in the early days where people weren’t considering the leakage out of that small cell into the external environment and potentially causing handover and revenue leakage issues.” He adds that the cost of small cell deployment is dropping and that Ranplan has developed a small cell and Wi-Fi deployment planning tool that uses algorithms to prevent small cells from being installed in inappropriate locations.

Williamson is seeing a lot of Wi-Fi system integrators diversifying into small cells, including a lot of Cisco value-added resellers. “These guys [Wi-Fi system integrators] are aggressive and they have a different mentality to the larger system integrators that have traditionally gone into the market to win that business.”

Distributed Antenna Systems (DAS) have been the traditional means of delivering multi-operator coverage in large venues with heavy footfall such as large shopping centres or stadiums. The CAPEX cost can stretch to more than a million pounds once basestation and installation costs are included. While operators have invested to equip high profile sites in the past, they are now seeking more of the funding from building owners and property developers. Johnson adds that once a venue drops below 50,000 square feet it’s nearer the “bottom of the league table” when it comes to operators’ interest in deploying multi-operator technology.

A recent development that has significantly improved the economics of multi-operator DAS is the ability to feed it from small cells rather than conventional base stations. Arqiva’s Freeman ssays that this has removed the need to install full sized LTE base stations (one per operator) and meant that only one leased line is required. While one small cell per operator is still needed, it is cheaper than the alternative. ThinkSmallCell’s Chambers explains that part of the appeal behind this approach is that feeding DAS with normal high power base stations is extremely inefficient as the high power RF signal coming out of them must first be heavily attenuated, wasting a great deal of energy in the process. A small cell approach is less costly to buy and requires far less electricity, physical space and air conditioning to operate.

Colin Eddison, technical director at Herbert In-Building Wireless Solutions, Zinwave’s system integrator channel partner for in-building DAS deployment, says an advantage small cells and DAS have over Wi-Fi is that in some cases a Wi-Fi access point’s data rate can be bottlenecked by being connected to a user on the edge of its range, which affects all other users connected to it. He adds that even very well-designed Wi-Fi systems will not offer the same data rates as their cellular counterparts, and if a Wi-Fi system is going to be used for voice it needs to be built with VoIP in mind.

Freeman explains that at present not many of these systems have been deployed in the UK, but there have been a few proof of concept trials. In addition, Zinwave presented an interface panel that connects up to four small cells to its UNItivity DAS platform at this year’s Mobile World Congress (shown right).

It seems that we shouldn’t be holding our breath for host-neutral small cells in the UK. While ip.access’ host-neutral Viper technology is being trialled in Brazil, over here the stumbling block appears to be the regulatory environment for spectrum sharing and operators’ willingness to share spectrum.

“Ofcom has set out its position in terms of spectrum sharing and it is concerned about the competitive implications,” says ip.access’ Johnson. “We want to better understand those concerns and try to address them. It seems to us that we are able to extend the range of competition, not undermine it.”

“Getting the operators working in a shared operating model is achievable but it does take a long time,” says OpenCell’s Payne. “It will be 18 to 24 months before this is sorted out and it may never happen.” He adds that he has seen some “willingness from operators to fully investigate a neutral-host model” and notes that the major networks are already sharing infrastructure so they’ve overcome similar obstacles before. However, industry opinion seems a little divided with Chambers saying: “UK operators are resisting the move towards sharing spectrum” at the moment.

One organisation to watch in this area is the MulteFire Alliance – its technology allows for the use of LTE in five GHz unlicensed spectrum with easy deployment and features a neutral-host access mode. The Alliance includes Ericsson, Huawei, Intel, Nokia, and Qualcomm and recently completed its Release 1.0 specification.

Johnson notes that one development that might influence spectrum sharing in the UK is 3’s purchase of UK Broadband, which includes “a wedge of 3.5 GHz spectrum”. This is the same band that is licensed in the US for shared access in the Citizens Broadband Service under the auspices of the Federal Communications Commission.

Small cells aren’t just about voice and data. Johnson says ip.access is integrating presence sensing, NB-IoT and Cat-M1 IoT connectivity into its Viper2020 small cells as a service platform. The former could allow (permissions and data privacy laws permitting) retailers to know if customers are online shopping while in their stores and, if so, whether they’re doing so through the retailer’s own website or a competitor’s. Huawei’s LampSite 3.0 indoor small cell solution, which will be available in the second half of this year, also provides IoT connectivity and support for multi-operator scenarios. This suggests it might be wise to think about small cells and their development before rushing off to invest in a separate form of connectivity for your in-building IoT devices.

If you’re struggling with cellular coverage it’s worth considering small cells, providing your building(s) are not a size that would justify a fully-fledged DAS. Even that divide is becoming fuzzy thanks to the use of small cell-fed DAS. While both 4G-only and host-neutral small cells are the industry’s future, it’s important to weigh up the benefits of holding out for cheaper technology against the cost of being without decent cellular coverage for a few more years.

Dos and Don'ts

Do consider if you need single operator or multi-operator coverage. If you’re looking to provide coverage to the public you’ll need the latter

Do look at the business case carefully. How much additional revenue can you expect from greater cellular coverage?

Do think about scale. If you’re large enough in both size and footfall it’s worth discussing the matter with your MNO(s)

Do shop around. If you just need single operator coverage then quite a few companies should be able to help you

Don’t forget to consider the other things you can do with LTE coverage

Don’t plan a corporate small cell deployment without factoring in your company’s approach to employee devices

Don’t expect neutral-host cells to be deployed commercially in the UK in the next few years

Don’t forget that for some time not all handsets will support voice-over-LTE. Until then you’ll need some 3G small cells to allow voice calls

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